1. Field of the Invention
The present invention relates to a process of dividing an endless, wide multi-layered web of packing material into a plurality of individual webs of equal width, and aseptically processing the individual webs by supplying the webs to a forming and filling station of a tubular bag packaging machine where the individual webs are formed into individual packages, filled, sealed and singled. It also relates to tubular bag packaging machine utilizing such a process.
2. Description of the Prior Art
For economically manufacturing tubular bags, it is known to slit a sheet of packing material into a plurality of strips of equal width, advancing the individual strips to a variety of shaping and filing pipes arranged in parallel with respect to one another, through suitable molding or shaping elements. The multiple lengthwise separation of the web of packing material is effected by longitudinal cutters provided ahead of the forming and filling pipes. This prior art method is exemplified by European Patent Application 0 719 634 A2. It is absolutely satisfactory in operation and requires no further explanation. To the extent that the web of packing material is a one-layered foil material, this method can be carried out also aseptically or on a tubular bag packaging machine designed for aseptic operation, wherein the web of packing material initially is subjected to a sterilization process and introduced immediately thereafter into a sterile chamber in the end region of which the longitudinal cutters and the shaping and loading pipes and their appertaining elements (shaping shoulders and foil-strip forming elements, lengthwise sealing tools) are also under sterile conditions.
However, this method cannot be readily employed if extremely high requirements are placed upon the preservation of the sterile condition, and if multi-layered packing material, i.e. laminated foil, is to be utilized. The layers of laminates are joined by adhesives during manufacture. As the application of such adhesives is not under aseptic conditions, the ingress of micro-organisms or germs in such laminated material cannot be prevented from occurring, which, during slitting the sheet of packing material into a plurality of individual webs of equal width, can be released in the area of the cutting edges. Nevertheless, this does not yet present the actual problem to be solved as it is readily possible to slit the web of packing sheet into individual webs prior to sterilization and to lead the individual webs through the sterilization station, thereby also reaching the germ-containing cutting edges of the individual webs and thus avoiding a re-contamination of the sterile chamber. However, at this point, the actual problem is encountered for it has proved to be extremely difficult and complex, if not impossible, to guide the individual webs which, as a rule, are relatively narrow, precisely through the comparatively extended sterile path of conveyance. In fact, such a guidance of the individual webs, in practice, is not realizable to secure a safe and smooth operation of a tubular bag packing machine. In addition, tensions are set free in the web of packing material during cutting, which are likely to result in an uncontrolled lateral edge pattern of the individual webs, rectification of which, in the path of conveyance, is impossible or would involve unreasonably high costs, as each individual web would have to be held under guiding control.
It is, therefore, an object of the invention so to design a tubular bag packing machine system as to insure sterilization also of the exposed longitudinal cutting edges of a multi-layered web of packing material lengthwise cut into a plurality of individual webs.
Another object of the invention resides in assuring that the advance in parallel of the individual webs within the machine to the shaping and loading station be carried out smoothly and without involving any additional efforts.
Moreover, it is an object of the invention to provide a suitable process enabling, in an easy way, both a sterilization of the cutting edges of the individual webs and a substantially precise guidance of the packing material cut lengthwise, down to the forming elements.
The above and other objects are accomplished according to one aspect of the invention with a process of dividing an endless, wide multi-layered web of packing material into a plurality of individual webs of equal width, and aseptically processing the individual webs by supplying the webs to a forming and filling station of a tubular bag packaging machine where the individual webs are formed into individual packages, filled, sealed and singled, which comprises the steps of laser-cutting elongated slits into the endless wide multi-layered web at a distance corresponding to the width of the individual webs to produce the individual webs, the slits extending through all layers of the web except for a web layer remote from the laser, which is only notched at least at selected distances, whereby the notched remote web layer holds the individual webs together, then sterilizing the laser-cut multi-layered web in a sterilization station, and conveying the sterilized, laser-cut multi-layered web in a sterile chamber to a number of tube-shaping and filling elements corresponding to the number of individual webs, the notched remote web layer being torn by the tube-shaping elements to separate the individual webs from each other.
According to one embodiment, the remote web layer is only notched along the entire length of the multi-layered web so that the entire notched or scored remote web layer holds the individual webs together.
According to another embodiment, the remote web layer is scored only at selected distances along the length of the multi-layered web to provide readily breakable bridges at these distances while the elongated slits extend through the remote web layer between the readily breakable bridges, in which case only the bridges hold the individual webs together.
According to another aspect of this invention, there is provided a tubular bag packaging machine for aseptically processing individual webs of a packing material by forming the individual webs into individual packages in a forming and filling station, where they are filled, sealed and singled in a sterile chamber, the forming and filling station including a number of tube-shaping and filling elements corresponding to the number of individual webs, which machine comprises a supply reel of an endless, wide multi-layered web of packing material, a sterilization station arranged upstream of the forming and filling station for sterilizing the web of packing material, and a conveyance path along which the endless, wide multi-layered web of packing material is conveyed from the supply reel to the sterilization station. A number of lasers corresponding to the number of tube-shaping elements minus one are arranged in the conveyance path for cutting elongated slits into the multi-layered web to divide the web into the individual webs. Means for controlling the lasers determine the depth and the length of the slits.
The whole problem is thereby solved in a simple and at the same time elegant way in that the multi-layered web or laminated sheet of packing material is cut lengthwise, prior to sterilization, but only to the extent that, on the one hand, merely a perforation or score is formed which subsequently will break easily, and, on the other hand, the web structure is still joined together to enable it to be readily conveyed and guided. The complete separation of the web of packing material into individual webs arises automatically directly ahead of the forming pipes because the adaptation of the individual webs to the tubular shape of the pipe breaks the scored remote web layer.
The feature of xe2x80x9conly notching the layer of the web of packing material remote from the laserxe2x80x9d will insure that in this area, too, all separating planes in the laminated foil are notched or scored to safeguard sterilization, while the scoring will easily break by lateral tensile stress. If the remote web layer is cut through, except for the scored bridges at selected distances, the slit lengths correspond to a multiple of the bridge widths, and the bridge widths and the slit lengths can be readily varied by a corresponding laser control in conformity with the layer material, the number of layers of the laminated sheet being variable.
Controllable lasers permitting or enabling such special scoring in the longitudinal direction are known and commercially available. It is common practice to utilize such lasers in the technical field of direct interest, yet in a completely different field of application, i.e. for providing attenuation lines or tear-off aids, as shown, for example, in DE-A-196 36 429 C1 and U.S. Pat. Nos. 5,158,499 and 5,630,308.
Since the individual webs in the practice of the invention are no longer fed to the shaping elements in a condition already separated but rather in a condition still joined together by the scored remote web layer, it will be necessary to insure that the individual webs still joined together move toward their tube-shaping elements, which include the so-called shaping shoulders of the forming pipes, in a substantially centered direction.
According to an advantageous feature, the web of packing material containing the individual webs still joined together is subjected to a web edge control for centering the individual webs with respect to their given tube-shaping elements in the sterile chamber, prior to their being fed toward the tube-shaping elements. For this purpose, the machine is provided with web edge control elements ahead of the forming pipes. It is advantageous to arrange the adjusting elements for the web guide contained in the sterile chamber outside the sterile chamber, including optoelectronic edge sensors on view windows of the sterile chamber. This is done in consideration of the required pre-sterilization of the sterile chamber upon placing a packaging machine of this type into operation to prevent, to the highest degree possible, the formation of hidden germs which are difficult to be reached by the introduced sterilizing agent.
Similarly, it has proved advantageous also to provide a web edge control, as known in packaging machine engineering, ahead of the laser cutting station, i.e. between the latter and the supply reel from which the web of packing material is withdrawn. Such a web edge control not contained in the sterile chamber insures, in an advantageous way, that the web of packing material discharged from the reel advances toward the laser in a manner already correctly guided in the central direction, thereby safeguarding that the longitudinal laser cuts result in substantially identical widths of the individual webs.
Further features, advantages and objects of the invention will become more apparent from the ensuing detailed description of now preferred embodiments taken in conjunction with the appended schematic drawings.